JPH0623814A - Method and device for monitoring resin weighing and plasticizing process of injection molding machine - Google Patents

Abstract

PURPOSE:To closely monitor the resin weighing and plasticizing process of an injection molding machine and exactly judge whether or not there is any abnormal condition during this process. CONSTITUTION:A rotating shaft 30 of a screw 12 is provided with a rotation angle position detector 34 for detecting a number of pitches of rotation angle equally produced by one complete revolution of the shaft, a moving arm 32 is provided with a moving position detector 36 for detecting the weighing starting and ending positions and a control part 42 activates a weighing part 44 to measure the total number of the pitches supplied from the rotation angle position detector from the weighing starting position and the weighing ending position. A comparing part 48 judges whether or not the difference between the reference total pitch number preset in a setting part 46 and the total pitch number thus obtained is within a predetermined allowable range and, if not, actuates an alarm 50.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for monitoring a resin melt plasticizing process in an in-line screw type injection molding machine.

[0002]

2. Description of the Related Art Generally, in an in-line screw type injection molding machine, a screw arranged in a barrel is rotationally driven to move the screw backward by a predetermined distance to melt and measure a predetermined amount of resin. When the screw moves forward again, the predetermined amount of the molten resin is injected into the mold to mold the product. Conventionally, the monitoring method of the measurement plasticization process in which the resin is melt-measured determines whether the time required from the start of measurement to the completion of measurement or the screw rotation speed by arbitrary measurement is compared with the reference value and the measured value. It was a thing.

Further, as disclosed in Japanese Utility Model Laid-Open No. 41920/1990, since the backward moving distance of the screw, that is, the measuring position of the resin by the screw can be calculated from the rotating angle of the screw, the rotating angle of the screw is detected and measured. A device for monitoring the amount of injected resin at the time has also been proposed.

[0004]

However, the above-mentioned monitoring method grasps the outline of the entire plasticizing process, and it is not possible to make a pass / fail judgment by detailed analysis. In particular, regarding the monitoring method of monitoring the screw rotation speed, the resolution of the screw rotation speed is often based on one rotation, and the sampling is often rounded per one rotation. Therefore, there is a problem that it is often not known whether the monitoring result is positive or negative.

Further, in the method of monitoring the rotation angle of the screw, the metering position can be determined only by the screw rotation angle when the resin supply amount during measurement is stable and maintains a steady state. The resin is in the form of pellets and the supply itself tends to be dense and dense, so it does not reach a steady state and constantly fluctuates. In some cases, the screw may slip. In addition, the screw retreating operation during metering differs depending on the amount of resin supplied per unit time and the viscosity state of the molten resin at the screw tip.To determine the correlation between the screw rotation angle and the metering stroke, the resin used, the heating temperature, and the rotation speed. A fairly large amount of data is needed for parameters such as (different shear heat generation). Therefore, as a practical matter, there is a problem that the amount of injected resin at the time of accurate measurement cannot be monitored only by the screw rotation angle.

Therefore, the object of the present invention is to monitor the resin measuring and plasticizing process of the injection molding machine in detail, to suddenly break the resin in the resin measuring and plasticizing process, to cause a resin bridge at the hopper hole,
An object of the present invention is to provide a resin measuring plasticizing process monitoring method and device for an injection molding machine, which can accurately determine an abnormal state due to a screw idling or the like.

[0007]

According to the method for monitoring a resin measuring plasticizing process of an injection molding machine according to the present invention, a screw is driven at a preset rotational speed to move the screw backward to melt the resin. In a method of monitoring a resin measuring plasticizing process of an injection molding machine for measuring, one rotation of a screw is equally divided into a large number of pitches, and all the above-mentioned pitches by the screw rotation in the measuring plasticizing process from the start of measurement to the completion of measurement are counted, It is characterized in that the accumulated total pitch number is compared with a preset reference total pitch number, and whether or not the difference is within a preset allowable range is monitored.

In this case, it is preferable that the reference total number of pitches is set to the cumulative total number of pitches counted in the weighing and plasticizing step at the time of molding a good product.

Further, in this case, the difference between the cumulative total number of pitches obtained by counting the number of pitches by the screw rotation in the weighing plasticizing process from the start of weighing to the completion of weighing and the preset total number of reference pitches are within a preset allowable range. It can also be set to generate an alarm when it goes off.

Further, the resin measuring plasticizing process monitoring device of the injection molding machine according to the present invention is an injection molding in which the screw is driven backward at a preset rotational speed to melt and measure the resin. In the plastic measuring process monitoring device of the machine, a rotation angle position detector that detects the rotation angle associated with screw rotation by equally dividing it into multiple rotation pitches, and a start position and measurement of the screw axial position A movement position detector that outputs a completion position signal, a measurement start position from the movement position detector and a measurement completion position signal are received, and the counting unit starts counting the number of pitches accompanying the screw rotation of the rotation angle position detector, and A control unit for notifying the completion of counting and a counting start signal from the control unit start and accumulate the counting of the number of pitches accompanying the screw rotation of the rotation angle position detector, A measuring unit that finishes counting the number of pitches by a completion signal, a setting unit that presets the reference total pitch number, and a reference total pitch number of the setting unit and the cumulative total pitch number counted by the measuring unit are compared. And a monitoring unit for monitoring whether or not the difference between the cumulative total number of pitches and the reference total number of pitches is within a preset allowable range, and generating an alarm when the difference is outside the allowable range. Is characterized by.

[0011]

According to the resin measuring plasticizing process monitoring method of the injection molding machine according to the present invention, one rotation of the screw during the resin measuring operation is equally divided into a plurality of pitches, and the screw rotation in the process from the start of the measurement to the completion of the measurement. Is monitored whether or not the difference between the accumulated total pitch number obtained by counting all the pitch numbers and the preset reference total pitch number is within the preset allowable range.

By setting the reference total number of pitches as the total number of pitches when molding a good product, it is possible to monitor the stability of resin supply in comparison with when molding a good product.

Further, according to the present invention, when the difference between the cumulative total pitch number and the reference total pitch number is out of the allowable range, an alarm is generated. Therefore, it is possible to reliably monitor the abnormal state of the resin measuring and plasticizing process, and prevent a metal contact accident with the barrel of the screw due to careless idle operation such as running out of raw material.

Further, according to the resin measuring plasticizing process monitoring device of the injection molding machine according to the present invention, the rotation angle associated with the screw rotation is precisely detected by equally dividing one rotation into a plurality of pitches by the rotation angle position detector. Then, the moving position detector detects the axial moving position of the screw and transmits the weighing start position and weighing completion position signals to the control unit. The control unit sends a command to the measuring unit to start or complete counting of the number of pitches accompanying the screw rotation of the rotation angle position detector in response to these position signals, whereby the measuring unit accumulates at the time of weighing. Measure the total number of pitches. Then, the cumulative total number of pitches and the reference total number of pitches preset in the setting unit are compared in the comparison unit, and it is monitored whether or not these differences are within the preset allowable range. When it comes off, an alarm is generated.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of a resin measuring plasticizing process monitoring method and apparatus of an injection molding machine according to the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is an explanatory diagram showing a schematic structure of an injection molding machine and a monitoring device structure of a resin measuring and plasticizing process according to an embodiment of the present invention. First, the injection molding machine will be briefly described. The screw 12 is arranged in the barrel 10, and the screw 12 is driven at a preset rotation speed via the rotation drive unit 14 to keep the screw 12 at a predetermined distance. Is moved backward, whereby a predetermined amount of the resin raw material 18 in the hopper 16 is melted and measured in the barrel space 10a. Then, the molten resin is injected into the mold (not shown) through the nozzle 22 by moving the screw 12 forward again through the moving cylinder 20, and the product is molded. .

However, in the present invention, in order to monitor the resin melting step, that is, the resin metering and plasticizing step, the rotary shaft 30 and the moving arm 32 of the screw 12 are monitored.
The rotation angle position detector 34 and the movement position detector 36 are provided in each of the above, and the former includes a measuring unit 44 that measures an output pulse of the rotation angle position detector 34 via an interface 38.
The latter is connected via the interface 40 to the control unit 42 that controls the measurement start and measurement completion of the measurement unit 44. The measuring unit 44 and the setting unit 46 for setting the reference value and the allowable value range are connected to the comparing unit 48, and the comparing unit 48 is connected to the alarm 50. Here, the rotation angle position detector 34 can detect the rotation angle with high accuracy by equally dividing one rotation of the screw into multiple pitches. In the case of an injection molding machine in which the rotation driving unit 14 performs measurement by an AC servo motor, a pulse encoder which is a rotation position detector of the servo motor itself can be used as the rotation angle position detector 34.

The resin measuring plasticizing process monitoring device of the injection molding machine thus configured operates as follows. The rotation angle position detector 34 generates a pulse corresponding to a pitch obtained by equally dividing one rotation of the screw into a large number of pitches. Screw 12
The measurement start position signal from the movement position detector 36 for detecting the movement position of the control unit 42 is transmitted to the control unit 42 via the interface 40, and the control unit 42 recognizes this signal and measures the measurement unit 44.
The rotation angle position detector 34 to the interface 3
A command signal is sent so as to start counting the number of pulses corresponding to the number of pitches related to the screw rotation sent via 8.
The measuring unit 44 starts counting the pulse number and accumulates it. When the counting of the counting unit 44 is completed, the control unit 42 recognizes the weighing completion position signal sent from the moving position detector 36 to the control unit 42 via the interface 40, similarly to the start of counting, and the counting end is completed. This is done by sending a command signal. In this way, the reference total number set in the setting section 46 is set as the reference value based on the cumulative total number of pitches measured in the resin measuring plasticizing process in the measuring section 44 and the total cumulative number of pitches previously counted at the time of molding a good product. The difference from the number of pitches is compared with the comparison unit 4
In step 8, it is compared with an allowable range of difference (set by + value and − value) which is also preset in the setting unit 46, and it is determined whether the difference is within the allowable range. This determination can be made because the amount of work actually operated (rotated) in the measuring process and the amount of injected molten resin have a correlation. The comparison unit 48
The alarm 50 is activated when it is out of the allowable range.

[0019]

As is apparent from the above-described embodiments, according to the present invention, the screw is driven at a preset rotation speed to move the screw backward and thereby melt-measure the resin. In the resin measuring plasticization process monitoring method of No. 1, one rotation of the screw is equally divided into a large number of pitches, all the number of pitches during the measuring operation from the start of measurement to the completion of measurement are counted, and the accumulated total number of pitches is preset. By monitoring whether the difference from the reference total pitch number is within the preset allowable range, it is possible to monitor the injection resin amount during accurate measurement of the molten resin and to detect abnormal conditions due to idle rotation such as raw material exhaustion. An alarm can be generated by making an accurate determination. As a result, a stable resin measuring and plasticizing process can be realized, and the molding quality can be improved.

Although the preferred embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various design changes can be made without departing from the spirit of the present invention. Is.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a schematic configuration and a monitoring device configuration of an injection molding machine as an embodiment of a resin measuring plasticizing process monitoring device of an injection molding machine according to the present invention.

[Explanation of symbols]

10 barrel 10a barrel space 12 screw 14 rotation drive unit 16 hopper 18 resin material 20 moving cylinder 22 nozzle 30 rotating shaft 32 moving arm 34 rotating angle position detector 36 moving position detector 38 interface 40 interface 42 control unit 44 measuring unit 46 setting Part 48 Comparison part 50 Alarm

Claims (4)

[Claims] 1. A method for monitoring a resin measuring plasticizing process of an injection molding machine, wherein a screw is driven at a preset rotational speed to move the screw backward to measure the resin melted. Equally divided into
Counting all the number of pitches by screw rotation in the weighing plasticizing process from the start of weighing to the completion of weighing, comparing the counted cumulative total number of pitches with the preset reference total number of pitches, and the difference is the preset tolerance A method for monitoring a resin measuring plasticizing process of an injection molding machine, which is characterized by monitoring whether or not it is within a range. 2. The resin measuring plasticizing process monitoring method for an injection molding machine according to claim 1, wherein the reference total pitch number is set as a cumulative total number of pitches counted in the measuring plasticizing process at the time of molding a good product. 3. When the difference between the cumulative total number of pitches obtained by counting the number of pitches due to screw rotation in the weighing plasticizing process from the start of weighing to the completion of weighing and the preset total number of reference pitches deviates from a preset allowable range. The method for monitoring a resin measuring and plasticizing process of an injection molding machine according to claim 1 or 2, wherein an alarm is generated. 4. A resin metering plasticizing process monitor of an injection molding machine, wherein a screw is driven at a preset rotational speed to move the screw backward to melt-measure the resin. Rotation angle position detector for detecting evenly divided multiple rotation pitches, a movement position detector for detecting the axial movement position of the screw and outputting a measurement start position and measurement completion position signal, and the movement position detector A control unit for receiving a measurement start position signal and a measurement completion position signal from the control unit and notifying the measurement unit of the start and end of counting of the number of pitches accompanying the screw rotation of the rotation angle position detector, and a counting start signal from the control unit. The measurement unit that starts and accumulates the number of pitches accompanying the screw rotation of the rotation angle position detector by the And a comparator for comparing the reference total pitch number of the setting unit with the cumulative total pitch number counted by the measuring unit. A resin measuring plasticizing process monitoring device for an injection molding machine, characterized in that it is configured to monitor whether a difference from the number is within a preset allowable range and to generate an alarm when the difference is outside the allowable value. .